They should all use the system with a mat on the ground.
i went to quote a hotel yesterday 3 storey with basement window on street with railing round this one http://www.roscoehouse-apartments.co.uk/trad cleaning doing it off a ladder reason being the client doesnt like the glass being broken all the time by wfp bowever there quite willing for the window cleaner to break bones and possibly kill himself one by falling hitting deck or two by impaling himself on the railingi said you know what i value my life and my staffs il let him keep this job at £45!!
if there is a fall, would the hse not have to be notified and also I know the cleaner is at fault but surely the school is liable as they are paying for the service..?graham